Radiesthesia is the art of measuring subtle energies. The main instruments used are the pendulum and dowsing rods. When doing radiesthetic work, the body of the person doing the measuring becomes part of the process. Therefore some training is recommended to achieve accurate results. Some people possess special abilities to perform radiesthetic measurements, but with some practice everyone can learn how to do it. Meanwhile, a wide range of literature is available for help. The most popular purpose of radiesthesia is tracking water resources and locating areas of harmful radiation. Radiesthesia is also applied in diagnostic medicine and for classification of food and medicine.